LOVE AND ADDICTION: VOLES IN LOVE JUST SAY NO TO SPEED

By Maia Szalavitz

While love doesn't always conquer all, it can be a potent antidote to addiction, according to a growing body of research. The latest study on the matter examined male prairie vole behavior, finding that those that had bonded to a female partner were less interested in taking amphetamine than bachelor voles.

"These results indicate that the pair-bonding experience decreased the rewarding properties of amphetamine," says Kimberly Young, an author of the study and a postdoctoral student at Florida State University.

Unlike rats or mice, prairie voles form lifelong bonds with their mates, more closely approximating human social behavior, which is why scientists like to study them. For the current research, which was published in the Journal of Neuroscience, researchers looked closely at how pair-bonding and amphetamine affected voles' brains.

The first experiment involved 30 male voles, 17 of which had been allowed to mate and form pair bonds; the rest were virgins. The voles were allowed to explore a set of two cages, connected by a tube, to see which cage they preferred. Then, the animals were given either amphetamine or a saline injection in the place that they did not like. The idea was to determine whether the voles would begin to prefer the cage in which they'd received the pleasurable drug. Only the virgin voles given amphetamine did.

In a second experiment, researchers studied brain activity in single and pair-bonded voles. They found that singletons derived more pleasure from amphetamine than the mated animals. In the bachelor voles, amphetamine increased the availability of dopamine D1 receptors in the nucleus accumbens, a pleasure-related region of the brain. In bonded voles, however, the availability of these receptors decreased.

"Amphetamine exposure had opposite neurobiological effects in sexually naïve and pair-bonded voles," Young notes.

But longtime vole researcher Larry Young of Emory University, who was not affiliated with the current research, expressed caution. "While this study is very interesting, it will be important to determine whether pair-bonded voles would be less likely to work for drugs of abuse if given unlimited access," he said in a statement. Like "place preference," determining how hard an animal will work to get drugs is another way to measure how pleasurable -- or, as regulators put it, "liable to abuse" -- a substance is.


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